462 Bulletin A?nencan Museum of Natural History. [Vol. XIX, 



111- 



posterior portion of the second centrum. The forked chev- 

 rons apparently begin at the posterior side of the third cau- 

 dal, the chevrons being intervertebral; the haemapophysial 

 canal is apparently closed in the first chevron. The firmly 

 coalesced caudal ribs of the anterior caudals are broad and 

 backwardly directed. With the supposed thirteenth caudal 

 there begins a gradual elongation of the zygapophyses, which 

 reaches a great development between the sixteenth and 

 twenty-fourth, the prezygapophyses being greatly elongated 

 and partly encircling the somewhat smaller postzygapophyses 

 of the preceding vertebrae. At the same 

 time the chevrons become depressed, bifur- 

 cate in front, with a deep posterior keel. 



The pelvic girdle is distinguished by the 

 deep symphysial union of the pubes, the 

 considerably more slender ischia, which are 

 in contact distally and proximally exhibit 

 two hooked processes; the ilium has a very 

 broad pubic and narrow ischial peduncle, 

 the pre- and post-acetabular portions of 

 the depressed crest are subequal. A very 

 distinctive feature of the postacetabular 

 crest is the hollowing out and inferior 

 expansion into a broad concave plate. 



In the fore limb there was some question 



as to the determination of the ulna and 



radius. The humerus is longer than these 



elements, measuring .127 m. The few 



phalanges preserved enable us to associate 



with this animal a relatively complete 



manus belonging to another individual, in 



which the striking elongation of the second 



digit, the comparative slenderness of the 



third and the atrophy of the fourth can 



be clearly made out. The palmar view of 



the manus somewhat suggests that of the two-toed sloth. 



The terminal phalanges are elongate, recurved, and laterally 



compressed, with a distinct lateral claw-groove. The some- 



Fig, 2. — Ornitholestes 

 herinanni. Amer. Mus. 

 No. 587. Palmar view 

 of left manus. X \. 



